The present invention relates to a model holder and an articulator for dental modelling and comprises an upper part and a lower part mutually connected by means of a hinge, which makes it possible to simulate a movement approximately corresponding to a chewing movement, between the upper part and the lower part as well as means for adjusting the upper part in relation to the lower part in order to establish a correct mutual engagement between the models mounted on the two parts and a subsequent fixation thereof. Moreover, the invention relates to an apparatus for adjusting such an articulator.
From U.S. Pat. No. 4,548,581 an articulator for denture modelling is known, said articulator consisting of a hinged two part flexible element, each part ending in a ball-and-socket joint placed in a mounting element. The mounting elements are provided with a pin adapted to be glued in a groove in a cast model, which in the examples given is a complete jaw model or mould of either an upper jaw or a lower jaw. After the mounting of the mounting elements the two models or casts can be adjusted to correct engagement corresponding to the the bite registered from the patient, after which the two ball-and-socket joints are fixated by means of an adhesive. The articular can on account of the combination of the hinge and the two ball-and-socket joints be fully adequately adjusted, but is, due to the fact that during the mounting and the adjustment thereof two subsequent glueing operations are required, fairly slow to work with. For dental modelling consisting of the restoration of single teeth or smaller bridges and the like tasks. Where no cast of the whole set of teeth is available, the known apparatus is akward to handle, and the use of the known apparatus involves an unreasonably big consumption of time for fastening the models on a suitable stanchion, to which the connecting parts may be glued. This fastening normally takes place by means of pins to be inserted into bores in the model, and which pins are moulded in the stanchion, the number of pins being of such a size that a single tooth can be cut out of the model and mounted separately.
It is known in connection with the production of models to cast these in a rectangular mould with toothed walls. The model can be removed from the toothed mould and reinserted after having been divided or worked up in other ways, and on account of the-toothing also parts of the model can be put back in the mould in the same place, in which they were originally moulded. The mould can be cast in an articulator which may later be adjusted, but in all quite a number of operations with subsequent setting is required to produce an applicable model of a denture.
The object of the present invention is to provide an articulator, which is characteristic by means of the subject matter of the characterizing clause of claim 1.
Through mounting of the hinge of the articulator on a stanchion made of thermoplastics, which can be plastified through heating and fixated in a new position by cooling and by combining these features therewith that the models are directly cast in the upper and lower part of the articulator, a number of working processes will be superfluous in connection with the making of the model, said operations being admittedly per se not very time-consuming, but which per se requires a setting time of several minutes for the plaster or the adhesive used. Besides, the articulator is simple to make and suitable for being used only once. The hinge of the articulator should be separable to make it possible immediately to cast the model in the toothed mould, which is integral with the remaining part of the upper or lower part.
Preferred embodiments will appear from the dependent claims. It is in particular advantageous that the models cast in the moulds can be taken out and worked up, for instance cut through, and that it is possible to place the individual pieces correctly in the articulator again. For this purpose the moulds are provided with index rulers and with means for providing a corresponding impression in the cast model. The index of the ruler ensures a completely accurate re-placing.
The single ball-and-socket joint forming the hinge of the articulator cannot exactly imitate the chewing movement obtained by the anatomical jaw hinge, and such an imitation is not required. It is of great importance that a correct engagement between the upper and lower part of the denture can be established. From this position of engagement the required movement is very small and may be obtained from the elasticity of the stanchion and the other parts. Therefore, an exact definition of the placing of the hinge vis a vis the moulds is unimportant and the stanchion may be placed anywhere at the edge of the form part.